1. Field of the Invention
The present invention relates to an exposure apparatus used to fabricate a semiconductor device and the like by projecting a designed pattern by exposure onto a resist on a substrate, and a device fabrication method capable of using the same.
2. Description of the Related Art
Conventionally, a stepper and a scanning exposure apparatus are known as exposure apparatuses of this sort. A stepper sequentially forms by exposure a mask pattern in a plurality of exposure regions on a substrate such as a wafer by using a projection optical system while moving the substrate step by step. A scanning exposure apparatus moves a mask and a substrate relative to a projection optical system and transfers the mask pattern onto the substrate by exposure by scanning the mask and the substrate with slit-like exposure light.
Also, a step-and-scan type exposure apparatus has been proposed recently to enable exposure of finer patterns with higher precision. This exposure apparatus projects a high-precision fine pattern by exposure in a plurality of regions on a substrate by repeating step movement and scan exposure. In this exposure apparatus, only light in a portion relatively close to the optical axis of a projection optical system is selectively used as exposure light through a slit. This enables exposure of finer patterns with higher precision. Additionally, in the scan exposure, a reticle stage and a wafer stage are moved in a scan direction or the like while being precisely controlled. For this purpose, the positions of these stages are monitored by using laser interferometers.
In scanning exposure apparatuses of the above sort, however, the accuracy of the movement of the reticle stage and the wafer stage in, e.g., the scan direction is unsatisfactory to be able to effectively expose finer patterns with high precision.